This thesis explores the early-time electronic relaxation in sodium iodide
aqueous solution exposed to a femtosecond ultra-violet laser pulse. Rather
than initiating the charge transfer reaction by resonant one-photon
photoexcitation of iodide, in the present time-resolved photoelectron
spectroscopy study the charge-transfer-to-solvent (CTTS) states are populated
via electronic excitation above the vacuum level. This is accomplished via a
two-photon process using 266 nm (4.65 eV) laser pulses with a pulse duration
of 60 fs. By analyzing the temporal evolution of electron yields from
ionization of two transient species, assigned to CTTS and its first excited
state, both their ultrafast population and relaxation dynamics were
determined. For ionization a femtosecond laser probe photon of 3.55 eV photon
energy is used. Comparison with resonant one-photon excitation studies shows
that the highly excited initial states populated in the present wotk exhibit
similar relaxation characteristics. Implications for structure and dynamical
response of the solvation cage are discussed. The measurements were conducted
using a newly constructed experimental setup and time-of-flight electron
spectrometer of the magnetic bottle type. The spectrometer was designed to
measure the energy spectra of electrons generated from liquids excited by a
strong laser field as well as by photons in the range from ultra-violet to
soft X-rays. Its energy resolution ΔE/E is approximately 0.016 at kinetic
energies of 100 eV. The collection efficiency of the spectrometer is
determined for different kinetic energies, and the values are discussed for
the magnetic-bottle configuration and the field-free arrangement.
Implementation of the recycle microjet technique offers uninterupted
measurement condition over several hours, which is advantageous for time-
resolved studies on diluted systems, and the possibility of recycling
expensive or rare sample.